Do we know that for sure? Roger is the only one whose arrest and death were confirmed and we know Shanks is seeing Rayleigh at least.
If this was stated in the manga, it would make more sense to discuss it, but making such deep analysis over SBS is a bit of a stretch
It's not really a deep analysis, it's simply what the Translation says,
It says that Roger Pirates were All surprised, it's clearly talking about when They were together,
It's not like Shanks went to look for handful few who survived & started showing off his Technique & convinced them that Roger never taught it to him
Sandman as well added that comment, so it's not really my analysis, He also concluded from what He read that Shanks did it at 15 & even Rayleigh couldn't do it,
This isn't a De-Hype for Rayleigh, it simply means that the Feat isn't impressive because Shanks just mimicked Roger's Movement,
The fact that Roger Pirates failed to do it, and it was implied that Roger's Instructions wd be needed if anyone tried to learn it, indicates that they agreed just from witnessing it that there are requirements for it that cannot be copied, and that's clearly adv. coc control
Also Sword Techniques are defined by what they create, not how they are performed,
For example, Zoro used Tatsumaki without Swords, why is it still Tatsu Maki? Cuz the Technique is named after what it creates, not what was used to create it, it's about creating a Tornado hence that name, regardless if Zoro used no swords or three or five swords or just metal bats
Same thing here or any technique, would Hiken be called Hiken if it was just the punch without any fire coming out?
Divine Departure is defined by what it unleashes & we've seen that it's an Adv. CoC Slash (Divine is clearly tied to it)
And again, Sandman also added such comment, that Shanks could probably use Adv. CoC since 15 year old,
I didn't add anything, i simply put his Translation (Statement from Oda himself) with what He concluded from it
This imo is a Hype for Shanks, Mihawk & Blackbeard, that's all.
I never said that they surpassed Roger at young age, i'm only saying that their Potential is possibly higher than him.